1. Field of the Invention
This invention relates to a guide rail for a drawing machine carriage with a one or more part track configuration that has a slot which runs longitudinally and from which the supporting arm of the carriage projects.
2. Description of the Prior Art
On drawing machine carriages, there is a horizontal carriage on horizontal guide rails which are mounted on the top face of the drawing board. A vertical carriage is mounted on the horizontal carriage, and the vertical carriage supports the drawing head and the drawing device and rules, etc. which are attached to it.
As a rule, the guide rails form a hollow track configuration. The known guide rails have a somewhat rectangular cross section and the side which points toward the drawing board is open and has lateral and symmetrically formed bearing surfaces along which the rollers of the carriage travel. The rollers of the carriage are on a support arm or mounting arm which projects from the area of the track configuration of the guide rail and serves for the mounting of either the vertical rail or the drawing head.
Extensive demands are made on the quiet, steady, constant, precise and easy motion of the carriage. The rollers and, if present, additional guide rails of the carriage, as well as the bearing surfaces of the guide rails, are therefore specially designed and exactly and precisely constructed.
One disadvantage of the known guide rails is that, after extensive operation, dust and dirt penetrate into the track configuration through the longitudinally extending opening out from which projects the mounting arm of the carriage.